[alsa-devel] [PATCH] ASoC: make snd_soc_dai_link more symmetrical

Jean-Francois Moine moinejf at free.fr
Tue Dec 31 18:44:30 CET 2013

On Tue, 31 Dec 2013 16:55:33 +0000
Mark Brown <broonie at kernel.org> wrote:

> On Thu, Dec 12, 2013 at 06:59:17PM +0100, Jean-Francois Moine wrote:
> > This patch renders optional the CODEC name / OF node on sound card register,
> > as it is done for the CPU side, in the case the CODEC DAI name is unique.
> > This simplifies the definition of CODECs with multiple DAIs, especially
> > in DTs, while keeping compatibility.
> So, this is similar to one of the comments I made on the DT patch you
> sent today: you're saying that this makes things better but you're not
> saying why it makes things better.  I've been sitting on this partly
> because I've been wanting to sit down and try to work out what the
> benefit is.  This information should be readily avaiable and omiting it
> seems like it will make things more fragile.
> If anything I'd expect DT to want to move towards specifying things by
> CODEC plus optional DAI index rather than anything else, that's the more
> common pattern for DT based things (really phandle plus index) and it's
> what the current generic card is doing.
> It's possible there is a benefit I'm just not seeing but you'll need to
> tell me.

The first benefit I got was in the front-end definition: the codec side
is the dummy codec, and this one has no phandle.

Then, finding the CODEC DAI from phandle asks for more code
(of_xlate_dai_name in the CODEC drivers) and finding it from the CODEC
name asks for a double loop in soc_bind_dai_link. On the other way, a
simple loop without any more change may be used when the DAI is simply
specified by its name. I would say that the DAI name is more meaningful
than a DAI index and that it is less subject to internal changes of the
CODEC driver.

Eventually, I don't think that, using only the name of the CODEC side
DAI to identify it, is not more fragile than identifying the CPU side
of the DAI link by its name.

Ken ar c'hentañ	|	      ** Breizh ha Linux atav! **
Jef		|		http://moinejf.free.fr/

More information about the Alsa-devel mailing list